Hybrid actuation devices including alignment aids

ABSTRACT

A hybrid actuation device that includes a first plate coupled to a second plate, a shape memory alloy wire coupled to the first plate, and an artificial muscle positioned between the first plate and the second plate. The artificial muscle includes a housing having an electrode region and an expandable fluid region, a first electrode and a second electrode each disposed in the electrode region of the housing and a dielectric fluid disposed within the housing. The expandable fluid region of the housing is positioned apart from a perimeter of the first plate and the second plate. A first alignment aid is positioned between the first plate and the first electrode, the first alignment aid having an inner surface facing the first plate and an outer surface facing the first electrode.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation of co-pending U.S. Pat.Application No. 17/545,027 filed on Dec. 8, 2022, for “Hybrid ActuationDevices Including Alignment Aids”, the entire disclosure of which ishereby incorporated by reference in its entireties, including thedrawings.

TECHNICAL FIELD

The present specification generally relates to hybrid actuation devicesthat include shape memory alloy materials and artificial muscles and,more particularly, hybrid actuation devices including alignment aids foraligning electrode pairs of the artificial muscles.

BACKGROUND

Current robotic technologies rely on rigid components, such asservomotors to perform tasks, often in a structured environment. Thisrigidity presents limitations in many robotic applications, caused, atleast in part, by the weight-to-power ratio of servomotors and otherrigid robotics devices. The field of soft robotics improves on theselimitations by using artificial muscles and other soft actuators.Artificial muscles attempt to mimic the versatility, performance, andreliability of a biological muscle. Some artificial muscles rely onfluid-based actuators. For example, certain artificial muscles mayintroduce fluid into and out of a volume to expand or contract theartificial muscles to perform mechanical work on a load. However, theseamount of force that current artificial muscles can exert is limited.

Accordingly, a need exists for improved actuation devices that includeartificial muscles.

SUMMARY

In one embodiment, a hybrid actuation device includes a first platecoupled to a second plate, a shape memory alloy wire coupled to thefirst plate, and an artificial muscle positioned between the first plateand the second plate. The artificial muscle includes a housing having anelectrode region and an expandable fluid region, a first electrode and asecond electrode each disposed in the electrode region of the housingand a dielectric fluid disposed within the housing. The expandable fluidregion of the housing is positioned apart from a perimeter of the firstplate and the second plate. A first alignment aid is positioned betweenthe first plate and the first electrode, the first alignment aid havingan inner surface facing the first plate and an outer surface facing thefirst electrode.

In another embodiment, a method of actuating a hybrid actuation deviceincludes actuating a shape memory alloy wire that is coupled to a firstplate of a plate pair further including a second plate, thereby drawingthe first plate and the second plate together, placing the hybridactuation device in an actuated state. A first alignment aid ispositioned between the first plate and an artificial muscle positionedbetween the first plate and the second plate. The artificial muscleincludes a housing having an electrode region and an expandable fluidregion, an electrode pair comprising a first electrode and a secondelectrode, each positioned in the electrode region of the housing, and adielectric fluid is housed within the housing. The method furtherincludes applying a voltage to the electrode pair, therebyelectrostatically attracting the first electrode and the secondelectrode together to hold the hybrid actuation device in the actuatedstate.

In a further embodiment, a hybrid actuation device includes a firstplate coupled to a second plate, at least one shape memory alloy wirecoupled to the first plate and configured to draw the first plate andthe second plate together to place the hybrid actuation device in anactuated state, and an artificial muscle positioned between the firstplate and the second plate. The artificial muscle includes an electrodepair configured to electrostatically attract and hold the hybridactuation device in the actuated state. A first alignment aid ispositioned between the first plate and the artificial muscle, the firstalignment aid having an inner surface facing the first plate and anouter surface facing the artificial muscle.

These and additional features provided by the embodiments describedherein will be more fully understood in view of the following detaileddescription, in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments set forth in the drawings are illustrative and exemplaryin nature and not intended to limit the subject matter defined by theclaims. The following detailed description of the illustrativeembodiments can be understood when read in conjunction with thefollowing drawings, where like structure is indicated with likereference numerals and in which:

FIG. 1A schematically depicts a side view of a hybrid actuation devicein a non-actuated state, according to one or more embodiments shown anddescribed herein;

FIG. 1B schematically depicts a side view of the hybrid actuation deviceof FIG. 1A in an actuated state, according to one or more embodimentsshown and described herein;

FIG. 2A schematically depicts a hybrid actuation device having aplurality of plate pairs arranged in an annular plate system that is ina non-actuated state, according to one or more embodiments shown anddescribed herein;

FIG. 2B schematically depicts the hybrid actuation device of FIG. 2A inan actuated state, according to one or more embodiments shown anddescribed herein;

FIG. 3 schematically depicts a spacer disposed between adjacent platepairs of the hybrid actuation device of FIG. 2A, according to one ormore embodiments shown and described herein;

FIG. 4 schematically depicts a hybrid actuation device having a platepair and an artificial muscles with a rectilinear shape, according toone or more embodiments shown and described herein;

FIG. 5 schematically depicts an exploded view of an example artificialmuscle, according to one or more embodiments shown and described herein;

FIG. 6 schematically depicts a top view of the artificial muscle of FIG.5 , according to one or more embodiments shown and described herein;

FIG. 7 schematically depicts a cross-sectional view of the artificialmuscle of FIG. 5 taken along line 7-7 in FIG. 6 in a non-actuated state,according to one or more embodiments shown and described herein;

FIG. 8 schematically depicts a cross-sectional view of the artificialmuscle of FIG. 5 taken along line 7-7 in FIG. 6 in an actuated state,according to one or more embodiments shown and described herein;

FIG. 9 schematically depicts a cross-sectional view of the artificialmuscle of FIG. 5 in a non-actuated state, according to one or moreembodiments shown and described herein;

FIG. 10 schematically depicts a cross-sectional view of the artificialmuscle of FIG. 5 in an actuated state, according to one or moreembodiments shown and described herein;

FIG. 11 schematically depicts an exploded view of another illustrativeartificial muscle, according to one or more embodiments shown anddescribed herein;

FIG. 12 schematically depicts a top view of the artificial muscle ofFIG. 11 , according to one or more embodiments shown and describedherein;

FIG. 13 schematically depicts a top view of another artificial muscle,according to one or more embodiments shown and described herein; and

FIG. 14 schematically depicts an actuation system for operating thehybrid actuation device of FIG. 1A-4, according to one or moreembodiments shown and described herein.

DETAILED DESCRIPTION

Embodiments described herein are directed to hybrid actuation devicesthat include a shape memory alloy (SMA) wire and an artificial muscle.The artificial muscle is positioned between and coupled to a plate paircomprising a first plate and a second plate that are hinged or otherwisecoupled together along an end of the plate pair. The artificial musclemay be a self-contained, fluidic artificial muscle. For example, theartificial muscle includes a housing having an electrode region and anexpandable fluid region, a first electrode and a second electrode eachdisposed in the electrode region of the housing, and a dielectric fluiddisposed within the housing. The artificial muscle is positioned suchthat the expandable fluid region is offset from a perimeter of the firstplate and the second plate of the plate pair. The SMA wire is coupled tothe plate pair such that application of a stimulant such as current flowin the SMA wire contracts the SMA wire and closes the plate pairtogether, placing the hybrid actuation device in an actuated state. Whenthe SMA wire contracts, drawing the plate pair together and placing thehybrid actuation device in the actuated state, the dielectric fluid isdirected into the expandable fluid region, expanding the expandablefluid region. Moreover, the first and second electrodeselectrostatically attract upon application of a voltage to hold thehybrid actuation device in the actuated state. This allows actuation(e.g., contraction) of the SMA wire to cease while retaining the hybridactuation device in the actuated state. Additionally, one or morealignment aids are provided to bring the first and second electrodesinto closer proximity with one another after actuated. The alignmentaids are positioned between a plate of the plate pair and a respectiveone of the first and second electrodes. The hybrid actuation devicecombines the actuation force achievable with an SMA wire and thedisplacement achievable with an artificial muscle to provide an improvedactuation device. Various embodiments of the hybrid actuation device andthe operation of which, are described in more detail herein. Wheneverpossible, the same reference numerals will be used throughout thedrawings to refer to the same or like parts.

Referring now to FIGS. 1A and 1B, a hybrid actuation device 10 isschematically depicted in a non-actuated state (FIG. 1A) and an actuatedstate (FIG. 1B). The hybrid actuation device includes a first plate 20Acoupled to a second plate 20B, for example, along a first end 22A, 22Bof each plate 20A, 20B to form a plate pair 30. The first plate 20A andthe second plate 20B each comprise a rigid material, such as a rigidpolymer, metal, ceramic, or the like. One example rigid polymer isacrylic. The first plate 20A and the second plate 20B are coupledtogether in a manner facilitating rotational motion of the first plate20A and the second plate 20B with respect to each other. For example,the first plate 20A and the second plate 20B may be coupled together bya hinge 15 along the first end 22A, 22B of each plate 20A, 20B. Eachplate 20A, 20B also includes a second end 24A, 24B opposite the firstend 22A, 22B and an outer surface 26A, 26B opposite an inner surface28A, 28B. In addition, the first plate 20A and the second plate 20Binclude a perimeter 25A, 25B.

Referring still to FIGS. 1A and 1B, the hybrid actuation device 10includes a first alignment aid 33A and a second alignment aid 33B. Eachalignment aid 33A, 33B has an outer surface 35A, 35B and an oppositeinner surface 37A, 37B. The first alignment aid 33A and the secondalignment aid 33B are provided on the first plate 20A and the secondplate B, respectively, by any suitable means such as, for example,adhesive, ultrasonic welding, and the like. More particularly, the outersurface 35A, 35B of the alignment aids 33A, 33B is fixed to the innersurface 28A, 28B of the plates 20A, 20B, respectively. As such, theouter surface 35A of the first alignment aid 33A faces the inner surface28A of the first plate 20A, and the outer surface 35B of the secondalignment aid 33B faces the inner surface 28B of the second plate 20B.

The alignment aids 33A, 33B may be either active aids, such that thealignment aids 33A, 33B or passive aids. As used herein, an active aidrefers to a structure that may be operated to expand or contract, orotherwise change size and/or shape, when receiving a current or voltage.Alternatively, as used herein, a passive aid refers to a staticstructure that is not operated to move or change size and/or shape whenreceiving a current or voltage. In embodiments in which the alignmentaids 33A, 33B are active aids, the alignment aids 33A, 33B may includean inflatable bladder structure. The inflatable bladder structure of thealignment aids 33A, 33B may be pneumatic and/or hydraulic.Alternatively, in embodiments in which the alignment aids 33A, 33B arepassive aids, the alignment aids 33A, 33B may include a deformable,compressible, or compliant material. Accordingly, the alignment aids33A, 33B may be formed from a compliant material that conforms to asurface of a corresponding one of the electrodes 106, 108. For example,the alignment aids 33A, 33B may include one or more leaf springs,three-dimensionally printed coils and/or windings, a foam substrate, arubber substrate, a gel substrate, and the like, or a combinationthereof. In embodiments, the alignment aids 33A, 33B may include afoldable origami structure such that the alignment aids 33A, 33B mayexpand and contract while in use. As used herein, “origami structure”refers to any structure having one or more folds that are capable offolding over one another and overlapping to save space in a verticaldirection such as a direction extending between one of the plates 20A,20B and a corresponding one of the electrodes 106, 108. In otherembodiments, the alignment aids 33A, 33B may include a honeycombstructure such that the alignment aids 33A, 33B may expand and contractwhile in use. As used herein, “honeycomb structure” refers to anystructure having an array of hollow cells formed between vertical wallsand, in shape, the cells are often columnar and hexagonal. Thesehoneycomb structures provide a material with minimal density andrelatively high out-of-plane compression properties. Further, it shouldbe appreciated that any combination of active aids and passive aids maybe utilized. For example, the first alignment aid 33A may be an activeaid and the second alignment aid 33B may be a passive aid, or viceversa.

Referring still to FIGS. 1A and 1B, the hybrid actuation device 10includes at least one artificial muscle 100 positioned between the firstplate 20A and the second plate 20B. The artificial muscle 100 includesan electrode pair 104 comprising a first electrode 106 and a secondelectrode 108 disposed in a housing 110 together with a dielectric fluid198. A “dielectric” fluid as used herein is a medium or material thattransmits electrical force without conduction and as such has lowelectrical conductivity. Some non-limiting example dielectric fluidsinclude perfluoroalkanes, transformer oils, and deionized water.

The housing 110 is coupled to the inner surface 28A of the first plate20A and the inner surface 28B of the second plate 20B. The electrodepair 104 is disposed in an electrode region 194 of the housing 110,adjacent an expandable fluid region 196. In operation, voltage may beapplied to the electrode pair 104, electrostatically attracting theelectrode pair 104 together. For example, voltage may be applied by apower supply 430A (FIG. 14 ), which is electrically coupled to theelectrode pair 104 by terminals 130, 152. Providing the voltage maycomprise generating the voltage, for example, in an embodiment in whichthe power supply 430A (FIG. 14 ) is a battery, converting the voltage,for example in embodiment in which the power supply 430A (FIG. 14 ) is apower adaptor, or any other known or yet to be developed technique forreadying a voltage for application. As depicted in FIGS. 1A and 1B, theexpandable fluid region 196 of the housing 110 is positioned apart froma perimeter 25A, 25B of the first plate 20A and the second plate 20B. InFIGS. 1A and 1B, the expandable fluid region 196 is positioned apartfrom the second end 24A, 24B of the first plate 20A and the second plate20B. Thus, the expandable fluid region 196 is not impeded from expandingwhen the first plate 20A and the second plate 20B are drawn together, asshown in FIG. 1B. As the housing 110 is coupled to the first plate 20Aand the second plate 20B via the first alignment aid 33A and the secondalignment aid 33B, respectively, electrostatic attraction between thefirst electrode 106 and the second electrode 108 holds the first plate20A and the second plate 20B together, holding the hybrid actuationdevice 10 in the actuated state, as depicted in FIG. 1B. In someembodiments, the first electrode 106 and the second electrode 108comprise a rectilinear shape. However, it should be understood thatother shapes and designs are contemplated, for example, as shown by theexample artificial muscles 101, 201, 301, 301′ described in more detailbelow with respect to FIGS. 5-13 .

The hybrid actuation device 10 further comprises at least one SMA wire50, for example, a first SMA wire 50A coupled to the first plate 20A anda second SMA wire 50B coupled to the second plate 20B. It should beunderstood that the hybrid actuation device 10 may comprise a single SMAwire 50, which may be coupled to both the first plate 20A and the secondplate 20B. In some embodiments, the first SMA wire 50A and the secondSMA wire 50B are two of a plurality of SMA wires 50 coupled to one orboth of the first plate 20A and the second plate 20B, for example, inthe embodiment described in more detail with respect to FIGS. 2A and 2B.

Referring still to FIGS. 1A and 1B, the first plate 20A and the secondplate 20B may each comprise at least one groove 27A, 27B extending intothe outer surfaces 26A, 26B of the first plate 20A and the second plate20B. As shown in FIGS. 1A and 1B, the first SMA wire 50A is positionedin the groove 27A extending into the outer surface 26A of the firstplate 20A and the second SMA wire 50B is positioned in a groove 27Bextending into the outer surface 26B of the second plate 20B. Inaddition, an adhesive layer 52A, 52B may be placed over each groove 27A,27B to hold the SMA wires 50A, 50B in their respective grooves 27A, 27B.

Each SMA wire 50 comprises a SMA material configured to contract inresponse to a stimulant, such as heat, current, or a magnetic field. Inoperation, a stimulant, such as the inducement of current flow withinthe SMA wire 50 may be applied to the SMA wire 50 by a power supply 430B(FIG. 14 ), which is electrically coupled to each SMA wire 50. Withoutintending to be limited by theory, in some embodiments, the power supply430B may generate a higher amperage and a lower voltage than the powersupply 430A as the SMA wire 50 is actuated by current and the electrodepair 104 is electrostatically attracted by voltage. In operation,applying the stimulant to each SMA wire 50 contracts each SMA wire 50and draws the first plate 20A and the second plate 20B together. Drawingthe first plate 20A and the second plate 20B together moves the hybridactuation device 10 from the non-actuated state, as shown in FIG. 1A, tothe actuated state, as shown in FIG. 1B. The SMA wire 50 may comprise(i) silver-cadmium, (ii) gold-cadmium, (iii) cobalt-nickel-aluminum,(iv) cobalt-nickel-gallium, (v) copper-aluminum-beryllium and at leastone of zirconium, boron, chromium, or gadolinium, (vi)copper-aluminum-nickel, (vii) copper-aluminum-nickel-hafnium, (viii)copper-tin, (ix) copper-zinc, (x) copper-zinc and at least one ofsilicon, aluminum, or tin, (xi) iron-manganese-silicon, (xii)iron-platinum, (xiii) manganese-copper, (xiv) nickel-iron-gallium (xv)nickel-titanium, (xvi) nickel-titanium-hafnium, (xvii)nickel-titanium-palladium, (xviii) nickel-manganese-gallium, (xix)titanium-niobium, or any combination thereof.

Referring still to FIGS. 1A and 1B, actuating the hybrid actuationdevice 10 comprises stimulating the at least one SMA wire 50, forexample, stimulating the first SMA wire 50A and the second SMA wire 50B,contracts at least one SMA wire 50 and draws the first plate 20A and thesecond plate 20B together. This places the hybrid actuation device 10 inan actuated state as depicted in FIG. 1B. Stimulating the at least oneSMA wire 50 comprises directing a current through the at least one SMAwire 50, heating the at least one SMA wire 50, and/or applying amagnetic field to the at least one SMA wire 50. When the first plate 20Aand the second plate 20B are drawn together, dielectric fluid 198disposed in the electrode region 194 of the housing 110 is directed intothe expandable fluid region 196, expanding the expandable fluid region196. In embodiments in which the alignment aids 33A, 33B are activeaids, a voltage may be applied to the alignment aids 33A, 33B to furthercompress the first electrode 106 and the electrode 108 toward oneanother. Next, the voltage may be applied to the electrode pair 104,electrostatically attracting the first electrode 106 and the secondelectrode 108 together to hold the hybrid actuation device 10 in theactuated state. Once the electrode pair 104 is drawn together by voltageapplication, the simulant may be removed from the at least one SMA wire50, expanding the at least one SMA wire 50. The continued application ofvoltage to the electrode pair 104 retains the hybrid actuation device 10in the actuated state. Thus, the electrostatic attraction of theelectrodes 106, 108 can keep the hybrid actuation device 10 actuatedwithout the negative thermal buildup of prolonged actuation of the atleast one SMA wire 50.

As discussed in more detail herein, the first electrode 106 and thesecond electrode 108 may be flexible and may not come into planarcontact with one another when the hybrid actuation device 10 is in theactuated state. As such, the alignment aids 33A, 33B being formed from adeformable material or configured to expand/contract, permitinner-facing surfaces of the first electrode 106 and the secondelectrode 108 to come into planar contact with one another, or at leastcloser to one another as compared to when the alignment aids 33A, 33Bare not provided, and thus facilitate a stronger attraction force. Itshould be appreciated that the alignment aids 33A, 33B may receive avoltage or current from the power supply 430A or 430B, or from aseparate power supply. In embodiments, the alignment aids 33A, 33B areactivated subsequent to the SMA wire 50 receiving a current.Alternatively, the alignment aids 33A, 33B are activated at the sametime as the SMA wire 50.

In operation, when the hybrid actuation device 10 is actuated bycontracting the at least one SMA wire 50, expansion of the expandablefluid region 196 produces a force of 25 Newton-millimeters (N.mm) percubic centimeter (cm³) of actuator volume or greater, such as 30 N.mmper cm³ or greater, 35 N.mm per cm³ or greater, 40 N.mm per cm³ orgreater, 45 N.mm per cm³ or greater, 50 N.mm per cm³ or greater, 55 N.mmper cm³ or greater, 60 N.mm per cm³ or greater, 70 N.mm per cm³ orgreater, 80 N.mm per cm³ or greater, 90 N.mm per cm³ or greater, 100N.mm per cm³ or greater, 125 N.mm per cm³ or greater, or any valuewithin a range having any two of these values as endpoints. In oneexample, the hybrid actuation device 10, 10′, 10″ may be actuated tolift a weight of 10.5 kilograms a displacement distance of 1 mm. Itshould be understood that increasing displacement distances arecontemplated, such as 1.5 mm or greater, 2 mm or greater, 5 mm orgreater, 10 mm or greater, or any value within a range having any two ofthese values as endpoints.

Referring now to FIGS. 2A and 2B, a hybrid actuation device 10′ isdepicted that comprises a plurality of plate pairs 30. In the hybridactuation device 10′, the first plate 20A and the second plate 20B ofeach of the plurality of plate pairs 30 have an annular sector shapesuch that the plurality of plate pairs 30 form an annular plate system31 comprising an opening 32 positioned in a central region of theannular plate system 31. In FIG. 2A, the hybrid actuation device 10′ isin the non-actuated state and in FIG. 2B, the hybrid actuation device10′ is in the actuated state. The opening 32 is bounded by the secondend 24A, 24B of the first and second plate 20A, 20B of each of theplurality of plate pairs 30. The expandable fluid region 196 of theartificial muscle 100 is positioned in the opening 32 of the annularplate system 31 such that expansion of the expandable fluid region 196is not impeded by actuation of the hybrid actuation device 10′. Becausethe first plate 20A and the second plate 20B of each of the plurality ofplate pairs 30 is an annular sector shape, the first end 22A, 22B of thefirst and second plates 20A, 20B comprises an outer curved edge 40 andthe second end 24A, 24B of the first and second plates 20A, 20Bcomprises an inner curved edge 42. In the embodiment depicted in FIGS.2A and 2B, the annular plate system 31 comprises a four plate pairs 30A,30B, 30C, and 30D. However, it should be understood that the annularplate system 31 may comprise any number of plate pairs 30 arranged in acollective annular shape. Although not shown, it should be appreciatedthat the hybrid actuation device 10′ further includes the alignment aids33A, 33B having a collective annular shape corresponding to that of theannular plate system 31 and including an opening formed therein to avoidimpeding the expandable fluid region 196.

In FIGS. 2A and 2B, the first plate 20A and the second plate 20B of eachof the plurality of plate pairs 30 are coupled together along theirrespective outer curved edges 40. For example, the first plate 20A andthe second plate 20B of each of the plurality of plate pairs 30 arecoupled together in a hinged connection, such as at the hinge 15, alongtheir respective outer curved edges 40. In some embodiments, the hybridactuation device 10′ includes an outer ring 38 surrounding the outercurved edges 40 of the plurality of plate pairs 30. The outer ring 38provides location for the hinged connection between first and secondplates 20A, 20B of the respective plate pairs 30. Indeed, in theembodiments of FIGS. 2A and 2B, the outer curved edges 40 of the firstand second plates 20A, 20B have an extended region 29 extending radiallyoutward toward the outer ring 38 and the hinged connection is located atthe connection point between the outer ring 38 and the extended regions29. Moreover, the arc length of the extended region 29 is less than thearc length of the outer curved edge 40, for example, from 10% to 40% ofthe arc length of the outer curved edge 40. This forms a gap between theouter ring 38 and a portion of the outer curved edges 40 of the platepairs 30.

Referring now to FIG. 2A-3 , the hybrid actuation device 10′ comprises aplurality of SMA wires 50 coupled to the plurality of plate pairs 30 ofthe annular plate system 31 in a concentric annular pattern. Forexample, the first plate 20A and the second plate 20B of each of theplate pairs 30 includes a plurality of grooves 27 positioned in aconcentric annular pattern and the plurality of SMA wires 50 arepositioned in the plurality of grooves 27. In addition, adhesive layers52 are positioned over the grooves 27 to hold the plurality of SMA wires50 in the plurality of grooves 27. As shown in FIG. 3 , a spacer 60 maybe disposed between adjacent plate pairs 30. The spacer 60 may beacrylic, however other materials are contemplated. The spacer 60 helpsto alignment and organize the plurality of SMA wires 50. For example,the spacer 60 includes a plurality of spacer holes 62. The plurality ofSMA wires 50 may be threaded through the plurality of spacer holes 62.In the hybrid actuation device 10′, the plurality of SMA wires 50 may becoupled to adjacent plate pairs 30 in an over/under thread pattern. Forexample, a first SMA wire 50A may be coupled to a first plate 20A of afirst plate pair 30A of the plurality of plate pairs 30 and a secondplate 20B (not pictured in FIG. 3 ) of a second plate pair 30B of theplurality of plate pairs 30 and a second SMA wire 50B may be coupled toa second plate 20B (not pictured in FIG. 3 ) of the first plate pair 30Aof the plurality of plate pairs 30 and a first plate 20A of the secondplate pair 30B of the plurality of plate pairs 30.

Referring now to FIG. 4 , another embodiment of a hybrid actuationdevice 10″ is depicted. As shown in FIG. 4 , the hybrid actuation device10″ comprising a single plate pair 30 comprising the first plate 20A andthe second plate 20B, which comprise a rectilinear shape. In FIG. 4 ,the first SMA wire 50A and the second SMA wire 50B are positioned alongopposite sides of the first plate 20A and the second plate 20B in athreaded pattern along each respective side. Furthermore, the hinge 15of the hybrid actuation device 10″ may comprise a Kevlar® thread. InFIG. 4 , the plate pair 30 and the artificial muscle 100 are each arectilinear shape. Indeed, FIG. 4 depicts that the hybrid actuationdevice 10, 10′, 10″ of the present disclosure is design independent.

Referring now to FIGS. 5-12 , example artificial muscles 101 (FIGS. 5-8), 201 (FIGS. 9 and 10 ), and 301 (FIGS. 11 and 12 ) are depicted. Theseartificial muscles 101, 201, 301 are examples that may be used as theartificial muscle 100 in the hybrid actuation device 10 of FIG. 1A-4.Moreover, it should be understood that these are merely some examplesthe artificial muscle 100 that may be used in the hybrid actuationdevice 10. It should further be understood that artificial muscles 101,201, 301 include additional components beyond those depicted by theartificial muscle 100 shown in FIG. 1A-4 and may be incorporated intothe artificial muscle 100.

Referring now to FIGS. 5-8 , the artificial muscle 101 includes thehousing 110, the electrode pair 104, including the first electrode 106and the second electrode 108, fixed to opposite surfaces of the housing110. The artificial muscles 101 also includes a first electricalinsulator layer 111 fixed to the first electrode 106, and a secondelectrical insulator layer 112 fixed to the second electrode 108. Insome embodiments, the housing 110 is a one-piece monolithic layerincluding a pair of opposite inner surfaces, such as a first innersurface 114 and a second inner surface 116, and a pair of opposite outersurfaces, such as a first outer surface 118 and a second outer surface120. In some embodiments, the first inner surface 114 and the secondinner surface 116 of the housing 110 are heat-sealable. In otherembodiments, the housing 110 may be a pair of individually fabricatedfilm layers, such as a first film layer 122 and a second film layer 124.Thus, the first film layer 122 includes the first inner surface 114 andthe first outer surface 118, and the second film layer 124 includes thesecond inner surface 116 and the second outer surface 120.

While the embodiments described herein primarily refer to the housing110 as comprising the first film layer 122 and the second film layer124, as opposed to the one-piece housing, it should be understood thateither arrangement is contemplated. In some embodiments, the first filmlayer 122 and the second film layer 124 generally include the samestructure and composition. For example, in some embodiments, the firstfilm layer 122 and the second film layer 124 each comprises biaxiallyoriented polypropylene. Moreover, the housing 110 may compriseadditional film layers For example, both the first film layer 122 andthe second film layer 124 may include multiple layers of material. Thus,the support thread 45 of FIGS. 2A and 2B may be positioned between theseadditional layers.

The first electrode 106 and the second electrode 108 are each positionedbetween the first film layer 122 and the second film layer 124. In someembodiments, the first electrode 106 and the second electrode 108 areeach aluminum-coated polyester such as, for example, Mylar®. Inaddition, one of the first electrode 106 and the second electrode 108 isa negatively charged electrode and the other of the first electrode 106and the second electrode 108 is a positively charged electrode. Forpurposes discussed herein, either electrode 106, 108 may be positivelycharged so long as the other electrode 106, 108 of the artificial muscle101 is negatively charged.

The first electrode 106 has a film-facing surface 126 and an oppositeinner surface 128. The first electrode 106 is positioned against thefirst film layer 122, specifically, the first inner surface 114 of thefirst film layer 122. In addition, the first electrode 106 includes thefirst terminal 130 extending from the first electrode 106 past an edgeof the first film layer 122 such that the first terminal 130 can beconnected to a power supply to actuate the first electrode 106.Specifically, the terminal 130 is coupled, either directly or in series,to a power supply and a controller of an actuation system 400, as shownin FIG. 14 . Similarly, the second electrode 108 has a film-facingsurface 148 and an opposite inner surface 150. The second electrode 108is positioned against the second film layer 124, specifically, thesecond inner surface 116 of the second film layer 124. The secondelectrode 108 includes the second terminal 152 extending from the secondelectrode 108 past an edge of the second film layer 124 such that thesecond terminal 152 can be connected to a power supply and a controllerof the actuation system 400 to actuate the second electrode 108.

The first electrode 106 includes two or more tab portions 132 and two ormore bridge portions 140. Each bridge portion 140 is positioned betweenadjacent tab portions 132, interconnecting these adjacent tab portions132. Each tab portion 132 has a first end 134 extending radially from acenter axis C of the first electrode 106 to an opposite second end 136of the tab portion 132, where the second end 136 defines a portion of anouter perimeter 138 of the first electrode 106. Each bridge portion 140has a first end 142 extending radially from the center axis C of thefirst electrode 106 to an opposite second end 144 of the bridge portion140 defining another portion of the outer perimeter 138 of the firstelectrode 106. Each tab portion 132 has a tab length L1 and each bridgeportion 140 has a bridge length L2 extending in a radial direction fromthe center axis C of the first electrode 106. The tab length L1 is adistance from the first end 134 to the second end 136 of the tab portion132 and the bridge length L2 is a distance from the first end 142 to thesecond end 144 of the bridge portion 140. The tab length L1 of each tabportion 132 is longer than the bridge length L2 of each bridge portion140. In some embodiments, the bridge length L2 is 20% to 50% of the tablength L1, such as 30% to 40% of the tab length L1.

In some embodiments, the two or more tab portions 132 are arranged inone or more pairs of tab portions 132. Each pair of tab portions 132includes two tab portions 132 arranged diametrically opposed to oneanother. In some embodiments, the first electrode 106 may include onlytwo tab portions 132 positioned on opposite sides or ends of the firstelectrode 106. In some embodiments, as shown in FIGS. 5 and 6 , thefirst electrode 106 includes four tab portions 132 and four bridgeportions 140 interconnecting adjacent tab portions 132. In thisembodiment, the four tab portions 132 are arranged as two pairs of tabportions 132 diametrically opposed to one another. Furthermore, asshown, the first terminal 130 extends from the second end 136 of one ofthe tab portions 132 and is integrally formed therewith.

Like the first electrode 106, the second electrode 108 includes at leasta pair of tab portions 154 and two or more bridge portions 162. Eachbridge portion 162 is positioned between adjacent tab portions 154,interconnecting these adjacent tab portions 154. Each tab portion 154has a first end 156 extending radially from a center axis C of thesecond electrode 108 to an opposite second end 158 of the tab portion154, where the second end 158 defines a portion of an outer perimeter160 of the second electrode 108. Due to the first electrode 106 and thesecond electrode 108 being coaxial with one another, the center axis Cof the first electrode 106 and the second electrode 108 are the same.Each bridge portion 162 has a first end 164 extending radially from thecenter axis C of the second electrode to an opposite second end 166 ofthe bridge portion 162 defining another portion of the outer perimeter160 of the second electrode 108. Each tab portion 154 has a tab lengthL3 and each bridge portion 162 has a bridge length L4 extending in aradial direction from the center axis C of the second electrode 108. Thetab length L3 is a distance from the first end 156 to the second end 158of the tab portion 154 and the bridge length L4 is a distance from thefirst end 164 to the second end 166 of the bridge portion 162. The tablength L3 is longer than the bridge length L4 of each bridge portion162. In some embodiments, the bridge length L4 is 20% to 50% of the tablength L3, such as 30% to 40% of the tab length L3.

In some embodiments, the two or more tab portions 154 are arranged inone or more pairs of tab portions 154. Each pair of tab portions 154includes two tab portions 154 arranged diametrically opposed to oneanother. In some embodiments, the second electrode 108 may include onlytwo tab portions 154 positioned on opposite sides or ends of the firstelectrode 106. In some embodiments, as shown in FIGS. 5 and 6 , thesecond electrode 108 includes four tab portions 154 and four bridgeportions 162 interconnecting adjacent tab portions 154. In thisembodiment, the four tab portions 154 are arranged as two pairs of tabportions 154 diametrically opposed to one another. Furthermore, asshown, the second terminal 152 extends from the second end 158 of one ofthe tab portions 154 and is integrally formed therewith.

Referring now to FIGS. 5-10 , at least one of the first electrode 106and the second electrode 108 has a central opening formed thereinbetween the first end 134 of the tab portions 132 and the first end 142of the bridge portions 140. In FIGS. 7 and 8 , the first electrode 106has a central opening 146. However, it should be understood that thefirst electrode 106 does not need to include the central opening 146when a central opening is provided within the second electrode 108, asshown in FIGS. 9 and 10 . Alternatively, the second electrode 108 doesnot need to include the central opening when the central opening 146 isprovided within the first electrode 106.

Referring to FIGS. 5-10 , the first electrical insulator layer 111 andthe second electrical insulator layer 112 have a geometry generallycorresponding to the first electrode 106 and the second electrode 108,respectively. Thus, the first electrical insulator layer 111 and thesecond electrical insulator layer 112 each have tab portions 170, 172and bridge portions 174, 176 corresponding to like portions on the firstelectrode 106 and the second electrode 108. Further, the firstelectrical insulator layer 111 and the second electrical insulator layer112 each have an outer perimeter 178, 180 corresponding to the outerperimeter 138 of the first electrode 106 and the outer perimeter 160 ofthe second electrode 108, respectively, when positioned thereon.

It should be appreciated that, in some embodiments, the first electricalinsulator layer 111 and the second electrical insulator layer 112generally include the same structure and composition. As such, in someembodiments, the first electrical insulator layer 111 and the secondelectrical insulator layer 112 each include an adhesive surface 182, 184and an opposite non-sealable surface 186, 188, respectively. Thus, insome embodiments, the first electrical insulator layer 111 and thesecond electrical insulator layer 112 are each a polymer tape adhered tothe inner surface 128 of the first electrode 106 and the inner surface150 of the second electrode 108, respectively.

Referring again to FIGS. 5-10 , the artificial muscle 101 is shown inits assembled form with the first terminal 130 of the first electrode106 and the second terminal 152 of the second electrode 108 extendingpast an outer perimeter of the housing 110, i.e., the first film layer122 and the second film layer 124. As shown in FIG. 6 , the secondelectrode 108 is stacked on top of the first electrode 106 and,therefore, the first electrode 106, the first film layer 122, and thesecond film layer 124 are not shown. In its assembled form, the firstelectrode 106, the second electrode 108, the first electrical insulatorlayer 111, and the second electrical insulator layer 112 are sandwichedbetween the first film layer 122 and the second film layer 124. Thefirst film layer 122 is partially sealed to the second film layer 124 atan area surrounding the outer perimeter 138 of the first electrode 106and the outer perimeter 160 of the second electrode 108. In someembodiments, the first film layer 122 is heat-sealed to the second filmlayer 124. Specifically, in some embodiments, the first film layer 122is sealed to the second film layer 124 to define a sealed portion 190surrounding the first electrode 106 and the second electrode 108. Thefirst film layer 122 and the second film layer 124 may be sealed in anysuitable manner, such as using an adhesive, heat sealing, or the like.

The first electrode 106, the second electrode 108, the first electricalinsulator layer 111, and the second electrical insulator layer 112provide a barrier that prevents the first film layer 122 from sealing tothe second film layer 124 forming an unsealed portion 192. The unsealedportion 192 of the housing 110 includes the electrode region 194, inwhich the electrode pair 104 is provided, and the expandable fluidregion 196, which is surrounded by the electrode region 194. The centralopenings 146, 168 of the first electrode 106 and the second electrode108 form the expandable fluid region 196 and are arranged to be axiallystacked on one another. Although not shown, the housing 110 may be cutto conform to the geometry of the electrode pair 104 and reduce the sizeof the artificial muscle 101, namely, the size of the sealed portion190. The dielectric fluid 198 is provided within the unsealed portion192 and flows freely between the first electrode 106 and the secondelectrode 108. It should be appreciated that the dielectric fluid 198may be injected into the unsealed portion 192 of the artificial muscle101 using a needle or other suitable injection device.

Referring now to FIGS. 7 and 8 , the artificial muscle 101 is actuatablebetween a non-actuated state and an actuated state. In the non-actuatedstate, the first electrode 106 and the second electrode 108 arepartially spaced apart from one another proximate the central openings146, 168 thereof and the first end 134, 156 of the tab portions 132,154. The second end 136, 158 of the tab portions 132, 154 remain inposition relative to one another due to the housing 110 being sealed atthe outer perimeter 138 of the first electrode 106 and the outerperimeter 160 of the second electrode 108. In the actuated state, asshown in FIG. 7 , the first electrode 106 and the second electrode 108are brought into contact with and oriented parallel to one another toforce the dielectric fluid 198 into the expandable fluid region 196.This causes the dielectric fluid 198 to flow through the centralopenings 146, 168 of the first electrode 106 and the second electrode108 and inflate the expandable fluid region 196. As noted above withrespect to FIG. 1A-4, when operating the hybrid actuation device 10,10′, 10″, contraction of the at least one SMA wire 50 brings theartificial muscle 101 into the actuated state, expanding the expandablefluid region 196 and electrostatic attraction between the firstelectrode and the second electrode 108 holds the artificial muscle 101and the hybrid actuation device 10, 10′, 10″ in the actuated state.

Referring now to FIG. 8 , the artificial muscle 101 is shown in thenon-actuated state. The electrode pair 104 is provided within theelectrode region 194 of the unsealed portion 192 of the housing 110. Thecentral opening 146 of the first electrode 106 and the central opening168 of the second electrode 108 are coaxially aligned within theexpandable fluid region 196. In the non-actuated state, the firstelectrode 106 and the second electrode 108 are partially spaced apartfrom and non-parallel to one another. Due to the first film layer 122being sealed to the second film layer 124 around the electrode pair 104,the second end 136, 158 of the tab portions 132, 154 are brought intocontact with one another. Thus, dielectric fluid 198 is provided betweenthe first electrode 106 and the second electrode 108, thereby separatingthe first end 134, 156 of the tab portions 132, 154 proximate theexpandable fluid region 196. Stated another way, a distance between thefirst end 134 of the tab portion 132 of the first electrode 106 and thefirst end 156 of the tab portion 154 of the second electrode 108 isgreater than a distance between the second end 136 of the tab portion132 of the first electrode 106 and the second end 158 of the tab portion154 of the second electrode 108. This results in the electrode pair 104zippering toward the expandable fluid region 196 when actuated. As notedabove with respect to FIG. 1A-4, the electrode pair 104 may zippertoward the expandable fluid region 196 when the at least one SMA wire 50of the hybrid actuation device 10, 10′, 10″ contracts. In someembodiments, the first electrode 106 and the second electrode 108 may beflexible. Thus, as shown in FIG. 5 , the first electrode 106 and thesecond electrode 108 are convex such that the second ends 136, 158 ofthe tab portions 132, 154 thereof may remain close to one another, butspaced apart from one another proximate the central openings 146, 168.In the non-actuated state, the expandable fluid region 196 has a firstheight H1.

When actuated, as shown in FIG. 9 , the first electrode 106 and thesecond electrode 108 zipper toward one another from the second ends 144,158 of the tab portions 132, 154 thereof, thereby pushing the dielectricfluid 198 into the expandable fluid region 196. As shown, when in theactuated state, the first electrode 106 and the second electrode 108 areparallel to one another. In the actuated state, the dielectric fluid 198flows into the expandable fluid region 196 to inflate the expandablefluid region 196. As such, the first film layer 122 and the second filmlayer 124 expand in opposite directions. In the actuated state, theexpandable fluid region 196 has a second height H2, which is greaterthan the first height H1 of the expandable fluid region 196 when in thenon-actuated state. Although not shown, it should be noted that theelectrode pair 104 may be partially actuated to a position between thenon-actuated state and the actuated state. This would allow for partialinflation of the expandable fluid region 196 and adjustments whennecessary.

In order to move the first electrode 106 and the second electrode 108toward one another or to electrostatically hold the first electrode 106and the second electrode 108 together, a voltage is applied by a powersupply (such as power supply 430A of FIG. 14 ). In some embodiments, avoltage of up to 10 kV may be provided from the power supply to inducean electric field through the dielectric fluid 198. The resultingattraction between the first electrode 106 and the second electrode 108pushes the dielectric fluid 198 into the expandable fluid region 196.Pressure from the dielectric fluid 198 within the expandable fluidregion 196 causes the first film layer 122 and the first electricalinsulator layer 111 to deform in a first axial direction along thecenter axis C of the first electrode 106 and causes the second filmlayer 124 and the second electrical insulator layer 112 to deform in anopposite second axial direction along the center axis C of the secondelectrode 108. Once the voltage being supplied to the first electrode106 and the second electrode 108 is discontinued, the first electrode106 and the second electrode 108 return to their initial, non-parallelposition in the non-actuated state.

It should be appreciated that the present embodiments of the artificialmuscle 101 disclosed herein, specifically, the tab portions 132, 154with the interconnecting bridge portions 174, 176, provide a number ofimprovements over actuators that do not include the tab portions 132,154, such as hydraulically amplified self-healing electrostatic (HASEL)actuators described in the paper titled “Hydraulically amplifiedself-healing electrostatic actuators with muscle-like performance” by E.Acome, S. K. Mitchell, T. G. Morrissey, M. B. Emmett, C. Benjamin, M.King, M. Radakovitz, and C. Keplinger (Science 05 Jan. 2018: Vol. 359,Issue 6371, pp. 61-65). Embodiments of the artificial muscle 101including two pairs of tab portions 132, 154 on each of the firstelectrode 106 and the second electrode 108, respectively, reduces theoverall mass and thickness of the artificial muscle 101, reduces theamount of voltage required during actuation, and decreases the totalvolume of the artificial muscle 101 without reducing the amount ofresulting force after actuation as compared to known HASEL actuatorsincluding donut-shaped electrodes having a uniform, radially-extendingwidth. More particularly, the tab portions 132, 154 of the artificialmuscle 101 provide zipping fronts that result in increased actuationpower by providing localized and uniform hydraulic actuation of theartificial muscle 101 compared to HASEL actuators including donut-shapedelectrodes. Specifically, one pair of tab portions 132, 154 providestwice the amount of actuator power per unit volume as compared todonut-shaped HASEL actuators, while two pairs of tab portions 132, 154provide four times the amount of actuator power per unit volume. Thebridge portions 174, 176 interconnecting the tab portions 132, 154 alsolimit buckling of the tab portions 132, 154 by maintaining the distancebetween adjacent tab portions 132, 154 during actuation. Because thebridge portions 174, 176 are integrally formed with the tab portions132, 154, the bridge portions 174, 176 also prevent leakage between thetab portions 132, 154 by eliminating attachment locations that providean increased risk of rupturing.

Moreover, the size of the first electrode 106 and the second electrode108 is proportional to the amount of displacement of the dielectricfluid 198. Therefore, when greater displacement within the expandablefluid region 196 is desired, the size of the electrode pair 104 isincreased relative to the size of the expandable fluid region 196. Itshould be appreciated that the size of the expandable fluid region 196is defined by the central openings 146, 168 in the first electrode 106and the second electrode 108. Thus, the degree of displacement withinthe expandable fluid region 196 may alternatively, or in addition, becontrolled by increasing or reducing the size of the central openings146, 168.

As shown in FIGS. 10 and 11 , another embodiment of an artificial muscle201 is illustrated. The artificial muscle 201 is substantially similarto the artificial muscle 101. As such, like structure is indicated withlike reference numerals. However, as shown, the first electrode 106 doesnot include a central opening. Thus, only the second electrode 108includes the central opening 168 formed therein. As shown in FIG. 8 ,the artificial muscle 201 is in the non-actuated state with the firstelectrode 106 being planar and the second electrode 108 being convexrelative to the first electrode 106. In the non-actuated state, theexpandable fluid region 196 has a first height H3. In the actuatedstate, as shown in FIG. 9 , the expandable fluid region 196 has a secondheight H4, which is greater than the first height H3. It should beappreciated that by providing the central opening 168 only in the secondelectrode 108 as opposed to both the first electrode 106 and the secondelectrode 108, the total deformation may be formed on one side of theartificial muscle 201. In addition, because the total deformation isformed on only one side of the artificial muscle 201, the second heightH4 of the expandable fluid region 196 of the artificial muscle 201extends further from a longitudinal axis perpendicular to the centralaxis C of the artificial muscle 201 than the second height H2 of theexpandable fluid region 196 of the artificial muscle 101 when all otherdimensions, orientations, and volume of dielectric fluid are the same.It should be understood that embodiments of the artificial muscle 201may be used as the artificial muscles 100 of the hybrid actuation device10 of FIG. 1A-4.

As shown in FIGS. 12 and 13 , another embodiment of an artificial muscle301 is illustrated. It should be appreciated that the artificial muscle301 includes similar structure as the artificial muscle 101 (FIGS. 6-9 )and therefore operates similarly in operation to the artificial muscle101 (FIGS. 6-9 ). Accordingly, the artificial muscle 301 describedherein may be incorporated in the hybrid actuation device 10 (FIGS.1A-1B). Notably, the artificial muscle 301 includes fan portions 332 inplace of the tab portions 132 discussed in relation to the artificialmuscle 100. However, it should be understood that both the fan portions332 of the artificial muscle 301 and the tab portions 132 are eachgenerally a radially extending portion of an electrode of an artificialmuscle, are positioned adjacent bridge portions, and provide a zippingfunctionality, as described above with respect to the artificial muscle101, and below with respect to the artificial muscle 301. Indeed, theseradially extending portions (e.g., tab portions and fan portions) eachprovide increased actuator power per unit volume, while minimizingbuckling and rupture during operation.

Referring now to FIGS. 12 and 13 , the artificial muscle 301 includes ahousing 302, an electrode pair 304, including a first electrode 306 anda second electrode 308, fixed to opposite surfaces of the housing 302, afirst electrical insulator layer 310 fixed to the first electrode 306,and a second electrical insulator layer 312 fixed to the secondelectrode 308. In some embodiments, the housing 302 is a one-piecemonolithic layer including a pair of opposite inner surfaces, such as afirst inner surface 314 and a second inner surface 316, and a pair ofopposite outer surfaces, such as a first outer surface 318 and a secondouter surface 320. In some embodiments, the first inner surface 314 andthe second inner surface 316 of the housing 302 are heat-sealable. Inother embodiments, the housing 302 may be a pair of individuallyfabricated film layers, such as a first film layer 322 and a second filmlayer 324. Thus, the first film layer 322 includes the first innersurface 314 and the first outer surface 318, and the second film layer324 includes the second inner surface 316 and the second outer surface320.

While reference may be made to the housing 302 including the first filmlayer 322 and the second film layer 324, as opposed to the one-piecehousing. It should be understood that either arrangement iscontemplated. In some embodiments, the first film layer 322 and thesecond film layer 324 generally include the same structure andcomposition. For example, in some embodiments, the first film layer 322and the second film layer 324 each comprises biaxially orientedpolypropylene.

The first electrode 306 and the second electrode 308 are each positionedbetween the first film layer 322 and the second film layer 324. In someembodiments, the first electrode 306 and the second electrode 308 areeach aluminum-coated polyester such as, for example, Mylar®. Inaddition, one of the first electrode 306 and the second electrode 308 isa negatively charged electrode and the other of the first electrode 306and the second electrode 308 is a positively charged electrode. Forpurposes discussed herein, either electrode 306, 308 may be positivelycharged so long as the other electrode 306, 308 of the artificial muscle301 is negatively charged.

The first electrode 306 has a film-facing surface 326 and an oppositeinner surface 328. The first electrode 306 is positioned against thefirst film layer 322, specifically, the first inner surface 314 of thefirst film layer 322. In addition, the first electrode 306 includes afirst terminal 330 extending from the first electrode 306 past an edgeof the first film layer 322 such that the first terminal 330 can beconnected to a power supply to actuate the first electrode 306.Specifically, the terminal is coupled, either directly or in series, toa power supply and a controller of the actuation system 400 (FIG. 14 ).Similarly, the second electrode 308 has a film-facing surface 348 and anopposite inner surface 350. The second electrode 308 is positionedagainst the second film layer 324, specifically, the second innersurface 316 of the second film layer 324. The second electrode 308includes a second terminal 352 extending from the second electrode 308past an edge of the second film layer 324 such that the second terminal352 can be connected to a power supply and a controller of the actuationsystem 400 (FIG. 14 ) to actuate the second electrode 308.

With respect now to the first electrode 306, the first electrode 306includes two or more fan portions 332 extending radially from a centeraxis C of the artificial muscle 301. In some embodiments, the firstelectrode 306 includes only two fan portions 332 positioned on oppositesides or ends of the first electrode 306. In some embodiments, the firstelectrode 306 includes more than two fan portions 332, such as three,four, or five fan portions 332. In embodiments in which the firstelectrode 306 includes an even number of fan portions 332, the fanportions 332 may be arranged in two or more pairs of fan portions 332.As shown in FIG. 10 , the first electrode 306 includes four fan portions332. In this embodiment, the four fan portions 332 are arranged in twopairs of fan portions 332, where the two individual fan portions 332 ofeach pair are diametrically opposed to one another.

Each fan portion 332 has a first side edge 332 a and an opposite secondside edge 332 b. As shown, the first terminal 330 extends from a secondend 336 of one of the fan portions 332 and is integrally formedtherewith. A channel 333 is at least partially defined by opposing sideedges 332 a, 332 b of adjacent fan portions 332 and, thus, extendsradially toward the center axis C. The channel 333 terminates at an end340 a of a bridge portion 340 interconnecting adjacent fan portions 332.

As shown in FIG. 13 , dividing lines D are included to depict theboundary between the fan portions 332 and the bridge portions 340. Thedividing lines D extend from the side edges 332 a, 332 b of the fanportions 332 to a first end 334 of the fan portions 332 collinear withthe side edges 332 a, 332 b. It should be understood that dividing linesD are shown in FIG. 10 for clarity and that the fan portions 332 areintegral with the bridge portions 340. The first end 334 of the fanportion 332, which extends between adj acent bridge portions 340,defines an inner length of the fan portion 332. Due to the geometry ofthe fan portion 332 tapering toward the center axis C between the firstside edge 332 a and the second side edge 332 b, the second end 336 ofthe fan portion 332 defines an outer length of the fan portion 332 thatis greater than the inner length of the fan portion 332.

Moreover, each fan portion 332 has a pair of corners 332 c defined by anintersection of the second end 336 and each of the first side edge 332 aand the second side edge 332 b of the fan portion 332. In embodiments,the corners 332 c are formed at an angle equal to or less than 90degrees. In other embodiments, the corners 332 c are formed at an acuteangle.

As shown in FIG. 13 , each fan portion 332 has a first side lengthdefined by a distance between the first end 334 of the fan portion 332and the second end 336 of the fan portion 332 along the first side edge332 a and the dividing line D that is collinear with the first side edge332 a. Each fan portion 332 also has a second side length defined by adistance between the first end 334 of the fan portion 332 and the secondend 336 of the fan portion 332 along the second side edge 332 b and thedividing line D that is collinear with the second side edge 332 b. Inembodiments, the first side length is greater than the second sidelength of the fan portion 332 such that the first electrode 306 has anellipsoid geometry.

The second end 336, the first side edge 332 a and the second side edge332 b of each fan portion 332, and the bridge portions 340interconnecting the fan portions 332 define an outer perimeter 338 ofthe first electrode 306. In embodiments, a central opening 346 is formedwithin the first electrode 306 between the fan portions 332 and thebridge portions 340, and is coaxial with the center axis C. Each fanportion 332 has a fan length extending from a perimeter 342 of thecentral opening 346 to the second end 336 of the fan portion 332. Eachbridge portion 340 has a bridge length extending from a perimeter 342 ofthe central opening 346 to the end 340 a of the bridge portion 340,i.e., the channel 333. As shown, the bridge length of each of the bridgeportions 340 is substantially equal to one another. Each channel 333 hasa channel length defined by a distance between the end 340 a of thebridge portion 340 and the second end of the fan portion 332. Due to thebridge length of each of the bridge portions 340 being substantiallyequal to one another and the first side length of the fan portions 332being greater than the second side length of the fan portions 332, afirst pair of opposite channels 333 has a channel length greater than achannel length of a second pair of opposite channels 333. As shown, awidth of the channel 333 extending between opposing side edges 332 a,332 b of adjacent fan portions 332 remains substantially constant due toopposing side edges 332 a, 332 b being substantially parallel to oneanother.

In embodiments, the central opening 346 has a radius of 2 centimeters(cm) to 5 cm. In embodiments, the central opening 346 has a radius of 3cm to 4 cm. In embodiments, a total fan area of each of the fan portions332 is equal to or greater than twice an area of the central opening346. It should be appreciated that the ratio between the total fan areaof the fan portions 332 and the area of the central opening 346 isdirectly related to a total amount of deflection of the first film layer322 when the artificial muscle 301 is actuated. In embodiments, thebridge length is 20% to 50% of the fan length. In embodiments, thebridge length is 30% to 40% of the fan length. In embodiments in whichthe first electrode 306 does not include the central opening 346, thefan length and the bridge length may be measured from a perimeter of animaginary circle coaxial with the center axis C.

Similar to the first electrode 306, the second electrode 308 includestwo or more fan portions 354 extending radially from the center axis Cof the artificial muscle 301. The second electrode 308 includessubstantially the same structure as the first electrode 306 and, thus,includes the same number of fan portions 354. Specifically, the secondelectrode 308 is illustrated as including four fan portions 354.However, it should be appreciated that the second electrode 308 mayinclude any suitable number of fan portions 354.

Each fan portion 354 of the second electrode 308 has a first side edge354 a and an opposite second side edge 354 b. As shown, the secondterminal 352 extends from a second end 358 of one of the fan portions354 and is integrally formed therewith. A channel 355 is at leastpartially defined by opposing side edges 354 a, 354 b of adjacent fanportions 354 and, thus, extends radially toward the center axis C. Thechannel 355 terminates at an end 362 a of a bridge portion 362interconnecting adjacent fan portions 354.

As shown in FIG. 13 , additional dividing lines D are included to depictthe boundary between the fan portions 354 and the bridge portions 362.The dividing lines D extend from the side edges 354 a, 354 b of the fanportions 354 to the first end 356 of the fan portions 354 collinear withthe side edges 354 a, 354 b. It should be understood that dividing linesD are shown in FIG. 10 for clarity and that the fan portions 354 areintegral with the bridge portions 362. The first end 356 of the fanportion 354, which extends between adjacent bridge portions 362, definesan inner length of the fan portion 354. Due to the geometry of the fanportion 354 tapering toward the center axis C between the first sideedge 354 a and the second side edge 354 b, the second end 358 of the fanportion 354 defines an outer length of the fan portion 354 that isgreater than the inner length of the fan portion 354.

Moreover, each fan portion 354 has a pair of corners 354 c defined by anintersection of the second end 358 and each of the first side edge 354 aand the second side edge 354 b of the fan portion 354. In embodiments,the corners 354 c are formed at an angle equal to or less than 90degrees. In other embodiments, the corners 354 c are formed at an acuteangle. During actuation of the artificial muscle 301, the corners 332 cof the first electrode 306 and the corners 354 c of the second electrode308 are configured to be attracted to one another at a lower voltage ascompared to the rest of the first electrode 306 and the second electrode308. Thus, actuation of the artificial muscle 301 initially at thecorners 332 c, 354 c results in the outer perimeter 338 of the firstelectrode 306 and the outer perimeter 360 of the second electrode 308being attracted to one another at a lower voltage and reducing thelikelihood of air pockets or voids forming between the first electrode306 and the second electrode 308 after actuation of the artificialmuscle 301.

As shown in FIGS. 12 and 13 , in embodiments, the first side edge 354 aof each fan portion 354 has a first side length defined by a distancebetween the first end 356 of the fan portion 354 and the second end 358of the fan portion 354 along the first side edge 354 a and the dividingline D that is collinear with the first side edge 354 a. Each fanportion 354 also has a second side length defined by a distance betweenthe first end 356 of the fan portion 354 and the second end 358 of thefan portion 354 along the second side edge 354 b and the dividing line Dthat is collinear with the second side edge 354 b. In embodiments, thefirst side length is greater than the second side length of the fanportion 354 such that the second electrode 308 has an ellipsoid geometrycorresponding to the geometry of the first electrode 306.

The second end 358, the first side edge 354 a and the second side edge354 b of each fan portion 354, and the bridge portions 362interconnecting the fan portions 354 define an outer perimeter 360 ofthe second electrode 308. In embodiments, a central opening 368 isformed within the second electrode 308 between the fan portions 354 andthe bridge portions 362, and is coaxial with the center axis C. Each fanportion 354 has a fan length extending from a perimeter 364 of thecentral opening 368 to the second end 358 of the fan portion 354. Eachbridge portion 362 has a bridge length extending from the centralopening 368 to the end 362 a of the bridge portion 362, i.e., thechannel 355. As shown, the bridge length of each of the bridge portions362 is substantially equal to one another. Each channel 355 has achannel length defined by a distance between the end 362 a of the bridgeportion 362 and the second end of the fan portion 354. Due to the bridgelength of each of the bridge portions 362 being substantially equal toone another and the first side length of the fan portions 354 beinggreater than the second side length of the fan portions 354, a firstpair of opposite channels 355 has a channel length greater than achannel length of a second pair of opposite channels 355. As shown, awidth of the channel 355 extending between opposing side edges 354 a,354 b of adjacent fan portions 354 remains substantially constant due toopposing side edges 354 a, 354 b being substantially parallel to oneanother.

In embodiments, the central opening 368 has a radius of 2 cm to 5 cm. Inembodiments, the central opening 368 has a radius of 3 cm to 4 cm. Inembodiments, a total fan area of each of the fan portions 354 is equalto or greater than twice an area of the central opening 368. It shouldbe appreciated that the ratio between the total fan area of the fanportions 354 and the area of the central opening 368 is directly relatedto a total amount of deflection of the second film layer 324 when theartificial muscle 301 is actuated. In embodiments, the bridge length is20% to 50% of the fan length. In embodiments, the bridge length is 30%to 40% of the fan length. In embodiments in which the second electrode308 does not include the central opening 368, the fan length and thebridge length may be measured from a perimeter of an imaginary circlecoaxial with the center axis C.

As described herein, the first electrode 306 and the second electrode308 each have a central opening 346, 368 coaxial with the center axis C.However, it should be understood that the first electrode 306 does notneed to include the central opening 346 when the central opening 368 isprovided within the second electrode 308. Alternatively, the secondelectrode 308 does not need to include the central opening 368 when thecentral opening 346 is provided within the first electrode 306.

Referring again to FIG. 12 , the first electrical insulator layer 310and the second electrical insulator layer 312 have a substantiallyellipsoid geometry generally corresponding to the geometry of the firstelectrode 306 and the second electrode 308, respectively. Thus, thefirst electrical insulator layer 310 and the second electrical insulatorlayer 312 each have fan portions 370, 372 and bridge portions 374, 376corresponding to like portions on the first electrode 306 and the secondelectrode 308. Further, the first electrical insulator layer 310 and thesecond electrical insulator layer 312 each have an outer perimeter 378,380 corresponding to the outer perimeter 338 of the first electrode 306and the outer perimeter 360 of the second electrode 308, respectively,when positioned thereon.

It should be appreciated that, in some embodiments, the first electricalinsulator layer 310 and the second electrical insulator layer 312generally include the same structure and composition. As such, in someembodiments, the first electrical insulator layer 310 and the secondelectrical insulator layer 312 each include an adhesive surface 382, 384and an opposite non-sealable surface 386, 388, respectively. Thus, insome embodiments, the first electrical insulator layer 310 and thesecond electrical insulator layer 312 are each a polymer tape adhered tothe inner surface 328 of the first electrode 306 and the inner surface350 of the second electrode 308, respectively.

Referring now to FIG. 13 , the artificial muscle 301 is shown in itsassembled form with the first terminal 330 of the first electrode 306and the second terminal 352 of the second electrode 308 extending pastan outer perimeter of the housing 302, i.e., the first film layer 322(FIG. 12 ) and the second film layer 324. The second electrode 308 isstacked on top of the first electrode 306 and, therefore, the first filmlayer 322 (FIG. 12 ) is not shown. In its assembled form, the firstelectrode 306, the second electrode 308, the first electrical insulatorlayer 310 (FIG. 12 ), and the second electrical insulator layer 312(FIG. 12 ) are sandwiched between the first film layer 322 (FIG. 12 )and the second film layer 324. The first film layer 322 (FIG. 12 ) ispartially sealed to the second film layer 324 at an area surrounding theouter perimeter 338 (FIG. 12 ) of the first electrode 306 and the outerperimeter 360 of the second electrode 308. In some embodiments, thefirst film layer 322 (FIG. 12 ) is heat-sealed to the second film layer324 (FIG. 12 ). Specifically, in some embodiments, the first film layer322 is sealed to the second film layer 324 to define a sealed portion390 surrounding the first electrode 306 and the second electrode 308.The first film layer 322 (FIG. 12 ) and the second film layer 324 may besealed in any suitable manner, such as using an adhesive, heat sealing,vacuum sealing, or the like.

The first electrode 306, the second electrode 308, the first electricalinsulator layer 310 (FIG. 12 ), and the second electrical insulatorlayer 312 (FIG. 12 ) provide a barrier that prevents the first filmlayer 322 (FIG. 12 ) from sealing to the second film layer 324, formingan unsealed portion 392. The unsealed portion 392 of the housing 302includes an electrode region 394, in which the electrode pair 304 isprovided, and an expandable fluid region 396, which is surrounded by theelectrode region 394. The central openings 346 (FIG. 12 ), 368 of thefirst electrode 306 and the second electrode 308 define the expandablefluid region 396 and are arranged to be axially stacked on one another.Although not shown, the housing 302 may be cut to conform to thegeometry of the electrode pair 304 and reduce the size of the artificialmuscle 301, namely, the size of the sealed portion 390. A dielectricfluid is provided within the unsealed portion 392 and flows freelybetween the first electrode 306 and the second electrode 308

Referring now to FIG. 13 , an alternative embodiment of an artificialmuscle 301′ is illustrated. It should be appreciated that the artificialmuscle 301′ is similar to the artificial muscle 301 described herein. Assuch, like structure is indicated with like reference numerals. Thefirst electrode 306 and the second electrode 308 of the artificialmuscle 301′ have a circular geometry as opposed to the ellipsoidgeometry of the first electrode 306 and the second electrode 308 of theartificial muscle 301 described herein. As shown in FIG. 12 , withrespect to the second electrode 308, a first side edge length of thefirst side edge 354 a is equal to a second side edge length of thesecond side edge 354 b. Accordingly, the channels 355 formed betweenopposing side edges 354 a, 354 b of the fan portions 354 each have anequal length. Although the first electrode 306 is hidden from view inFIG. 12 by the second electrode 308, it should be appreciated that thefirst electrode 306 also has a circular geometry corresponding to thegeometry of the second electrode 308.

Referring again to FIGS. 11 and 12 , actuation of the artificial muscle301 will be discussed. In the non-actuated state, the first electrode306 and the second electrode 308 are partially spaced apart from oneanother proximate the central openings 346, 368 thereof and the firstend 334, 356 of the fan portions 332, 354. The second end 336, 358 ofthe fan portions 332, 354 remain in position relative to one another dueto the housing 302 being sealed at the outer perimeter 338 of the firstelectrode 306 and the outer perimeter 360 of the second electrode 308.In the actuated state, the first electrode 306 and the second electrode308 are brought into contact with and oriented parallel to one anotherto force the dielectric fluid into the expandable fluid region 396. Thiscauses the dielectric fluid to flow through the central openings 346,368 of the first electrode 306 and the second electrode 308 and inflatethe expandable fluid region 396.

In the non-actuated state, a distance between the first end 334 of thefan portion 332 of the first electrode 306 and the first end 356 of thefan portion 354 of the second electrode 308 is greater than a distancebetween the second end 336 of the fan portion 332 of the first electrode306 and the second end 358 of the fan portion 354 of the secondelectrode 308. This results in the electrode pair 304 zippering towardthe expandable fluid region 396 when actuated. When actuated, the firstelectrode 306 and the second electrode 308 zipper toward one anotherfrom the second ends 336, 358 of the fan portions 332, 354 thereof,thereby pushing the dielectric fluid into the expandable fluid region396. When in the actuated state, the first electrode 306 and the secondelectrode 308 are parallel to one another. In the actuated state, thedielectric fluid flows into the expandable fluid region 396 to inflatethe expandable fluid region 396. As such, the first film layer 322 andthe second film layer 324 expand in opposite directions.

Referring now to FIG. 14 , an actuation system 400 may be provided foroperating the hybrid actuation device 10, in particular, operate theartificial muscle 100 and SMA wire 50 of the hybrid actuation device 10.The actuation system 400 may comprise a controller 410, an operatingdevice 420, the power supply 430A, the power supply 430B, a displaydevice 440, network interface hardware 450, and a communication path 405communicatively coupled these components, some or all of which may bedisposed in the onboard control unit 402.

The controller 410 may comprise a processor 412 and a non-transitoryelectronic memory 414 to which various components are communicativelycoupled. In some embodiments, the processor 412 and the non-transitoryelectronic memory 414 and/or the other components are included within asingle device. In other embodiments, the processor 412 and thenon-transitory electronic memory 414 and/or the other components may bedistributed among multiple devices that are communicatively coupled. Thecontroller 410 may include non-transitory electronic memory 414 thatstores a set of machine-readable instructions. The processor 412 mayexecute the machine-readable instructions stored in the non-transitoryelectronic memory 414. The non-transitory electronic memory 414 maycomprise RAM, ROM, flash memories, hard drives, or any device capable ofstoring machine-readable instructions such that the machine-readableinstructions can be accessed by the processor 412. Accordingly, theactuation system 400 described herein may be implemented in any computerprogramming language, as pre-programmed hardware elements, or as acombination of hardware and software components. The non-transitoryelectronic memory 414 may be implemented as one memory module or aplurality of memory modules.

In some embodiments, the non-transitory electronic memory 414 includesinstructions for executing the functions of the actuation system 400.The instructions may include instructions for operating the hybridactuation device 10, for example, instructions for actuating theartificial muscles 100 and actuating the at least one SMA wires 50.

The processor 412 may be any device capable of executingmachine-readable instructions. For example, the processor 412 may be anintegrated circuit, a microchip, a computer, or any other computingdevice. The non-transitory electronic memory 414 and the processor 412are coupled to the communication path 405 that provides signalinterconnectivity between various components and/or modules of theactuation system 400. Accordingly, the communication path 405 maycommunicatively couple any number of processors with one another, andallow the modules coupled to the communication path 405 to operate in adistributed computing environment. Specifically, each of the modules mayoperate as a node that may send and/or receive data. As used herein, theterm “communicatively coupled” means that coupled components are capableof exchanging data signals with one another such as, for example,electrical signals via conductive medium, electromagnetic signals viaair, optical signals via optical waveguides, and the like.

As schematically depicted in FIG. 14 , the communication path 405communicatively couples the processor 412 and the non-transitoryelectronic memory 414 of the controller 410 with a plurality of othercomponents of the actuation system 400. For example, the actuationsystem 400 depicted in FIG. 14 includes the processor 412 and thenon-transitory electronic memory 414 communicatively coupled with theoperating device 420 and the power supplies 430A, 430B.

The operating device 420 allows for a user to control operation of theartificial muscles 100 and the SMA wire 50 of the hybrid actuationdevice 10. In some embodiments, the operating device 420 may be aswitch, toggle, button, or any combination of controls to provide useroperation. The operating device 420 is coupled to the communication path405 such that the communication path 405 communicatively couples theoperating device 420 to other modules of the actuation system 400. Theoperating device 420 may provide a user interface for receiving userinstructions as to a specific operating configuration of the hybridactuation device 10, such as an amount desired actuation.

The power supplies 430A, 430B, generally referred to herein as powersupply 430, provide power to the one or more artificial muscles 100 andthe at least one SMA wire 50, respectively, of the hybrid actuationdevice 10. In some embodiments, the power supply 430 is a rechargeabledirect current power supply. It is to be understood that the powersupply 430 may be a single power supply or battery for providing powerto the one or more artificial muscles 100 and the at least one SMA wire50 of the hybrid actuation device 10. A power adapter (not shown) may beprovided and electrically coupled via a wiring harness or the like forproviding power to the one or more artificial muscles 100 and the atleast one SMA wire 50 of the hybrid actuation device 10 via the powersupply 430. Indeed, the power supply 430 is a device that can receivepower at one level (e.g., one voltage, power level, or current) andoutput power at a second level (e.g., a second voltage, power level, orcurrent).

In some embodiments, the actuation system 400 also includes a displaydevice 440. The display device 440 is coupled to the communication path405 such that the communication path 405 communicatively couples thedisplay device 440 to other modules of the actuation system 400. Thedisplay device 440 may be located on the hybrid actuation device 10, forexample, as part of the onboard control unit 402, and may output anotification in response to an actuation state of hybrid actuationdevice 10 or indication of a change in the actuation state of the hybridactuation device 10. The display device 440 may be a touchscreen that,in addition to providing optical information, detects the presence andlocation of a tactile input upon a surface of or adjacent to the displaydevice 440. Accordingly, the display device 440 may include theoperating device 420 and receive mechanical input directly upon theoptical output provided by the display device 440. For example, a usermay be able to specify a desired actuation pressure value.

In some embodiments, the actuation system 400 includes network interfacehardware 450 for communicatively coupling the actuation system 400 to aportable device 460 via a network 470. The portable device 460 mayinclude, without limitation, a smartphone, a tablet, a personal mediaplayer, or any other electric device that includes wirelesscommunication functionality. The portable device 460 may correspond toan infotainment device, or any other type of device capable ofcommunicating with the network interface hardware 450, utilizing Wi-Fi,Bluetooth, and/or any other suitable communication protocol. It is to beappreciated that, when provided, the portable device 460 may serve toprovide user commands to the controller 410, instead of the operatingdevice 420. As such, a user may be able to control or set a program forcontrolling the hybrid actuation device 10 utilizing the controls of theoperating device 420. Thus, the hybrid actuation device 10 may becontrolled remotely via the portable device 460 wirelessly communicatingwith the controller 410 via the network 470. For example, the user maybe able to specify a desired actuation force value.

It should now be understood that embodiments described herein aredirected to hybrid actuation devices that include an SMA wire and anartificial muscle. The artificial muscle is positioned between andcoupled to a plate pair and the SMA wire is coupled to the plate pair.Application of a stimulant such as current flow in the SMA wirecontracts the SMA wire and closes the plate pair together, placing thehybrid actuation device in an actuated state. First and secondelectrodes of the artificial muscle electrostatically attract uponapplication of a voltage to hold the hybrid actuation device in theactuated state allowing actuation (e.g., contraction) of the SMA wire tocease while retaining the hybrid actuation device in the actuated state.Additionally, one or more alignment aids are provided to bring the firstand second electrodes into closer proximity with one another afteractuated. The alignment aids are positioned between a plate of the platepair and a respective one of the first and second electrodes. The hybridactuation device combines the actuation force achievable with an SMAwire and the displacement achievable with an artificial muscle toprovide an improved actuation device.

It is noted that the terms “substantially” and “about” may be utilizedherein to represent the inherent degree of uncertainty that may beattributed to any quantitative comparison, value, measurement, or otherrepresentation. These terms are also utilized herein to represent thedegree by which a quantitative representation may vary from a statedreference without resulting in a change in the basic function of thesubject matter at issue.

While particular embodiments have been illustrated and described herein,it should be understood that various other changes and modifications maybe made without departing from the scope of the claimed subject matter.Moreover, although various aspects of the claimed subject matter havebeen described herein, such aspects need not be utilized in combination.It is therefore intended that the appended claims cover all such changesand modifications that are within the scope of the claimed subjectmatter.

What is claimed is:
 1. A hybrid actuation device comprising: a firstplate coupled to a second plate; a shape memory alloy wire coupled tothe first plate; an artificial muscle positioned between the first plateand the second plate, wherein the artificial muscle comprises: a housinghaving an electrode region and an expandable fluid region; and a firstelectrode and a second electrode each disposed in the electrode regionof the housing; and a first alignment aid positioned between the firstplate and the first electrode.
 2. The hybrid actuation device of claim1, further comprising a second alignment aid positioned between thesecond plate and the second electrode, the first alignment aid having aninner surface facing the first place and an outer surface facing thefirst electrode, the second alignment aid having an inner surface facingthe second plate and an outer surface facing the second electrode. 3.The hybrid actuation device of claim 2, wherein the inner surface of thefirst alignment aid is fixed to the first plate and the inner surface ofthe second alignment aid is fixed to the second plate.
 4. The hybridactuation device of claim 2, wherein the first alignment aid and thesecond alignment aid each comprises an inflatable bladder.
 5. The hybridactuation device of claim 2, wherein the first alignment aid and thesecond alignment aid each comprises at least one of a leaf spring, athree-dimensionally printed coil, a foam substrate, a rubber substrate,a foldable origami structure, a honeycomb structure, and a gelsubstrate.
 6. The hybrid actuation device of claim 1, wherein the shapememory alloy wire is a first shape memory alloy wire and a second shapememory alloy wire is coupled to the second plate.
 7. The hybridactuation device of claim 1, wherein the first plate and the secondplate form a first plate pair and the hybrid actuation device furthercomprises a plurality of plate pairs each comprising a first platecoupled to a second plate.
 8. The hybrid actuation device of claim 7,further comprising a spacer disposed between adjacent plate pairs of theplurality of plate pairs.
 9. The hybrid actuation device of claim 7,wherein the first plate and the second plate of each of the plurality ofplate pairs have an annular sector shape such that the plurality ofplate pairs form an annular plate system comprising an openingpositioned in a central region of the annular plate system and theexpandable fluid region of the housing is positioned in the opening ofthe annular plate system.
 10. The hybrid actuation device of claim 9,wherein the shape memory alloy wire is one of a plurality of shapememory alloy wires coupled to the plurality of plate pairs of theannular plate system in a concentric annular pattern.
 11. The hybridactuation device of claim 8, wherein the shape memory alloy wire iscoupled to a first plate of a first plate pair of the plurality of platepairs and a second plate of a second plate pair of the plurality ofplate pairs.
 12. The hybrid actuation device of claim 1, wherein thefirst alignment aid is formed from a compliant material that conforms toa surface of the first electrode.
 13. The hybrid actuation device ofclaim 1, wherein: the first electrode and the second electrode eachcomprise two or more radially extending portions and two or more bridgeportions; each of the two or more bridge portions interconnects adjacentradially extending portions; and at least one of the first electrode andthe second electrode comprises a central opening positioned between thetwo or more radially extending portions and encircling the expandablefluid region.
 14. A method of actuating a hybrid actuation device, themethod comprising: actuating a shape memory alloy wire that is coupledto a first plate of a plate pair further comprising a second plate,thereby drawing the first plate and the second plate together, placingthe hybrid actuation device in an actuated state, wherein a firstalignment aid is positioned between the first plate and an artificialmuscle positioned between the first plate and the second plate, theartificial muscle comprising: a housing having an electrode region andan expandable fluid region; and an electrode pair comprising a firstelectrode and a second electrode, each positioned in the electroderegion of the housing; and applying a voltage to the electrode pair,thereby electrostatically attracting the first electrode and the secondelectrode together to hold the hybrid actuation device in the actuatedstate.
 15. The method of claim 14, wherein the first alignment aidcomprises an inflatable bladder.
 16. The method of claim 14, wherein thefirst alignment aid comprises at least one of a leaf spring, athree-dimensionally printed coil, a foam substrate, a rubber substrate,and a gel substrate.
 17. The method of claim 14, wherein the shapememory alloy wire is a first shape memory alloy wire and the methodfurther comprises actuating a second shape memory alloy wire that iscoupled to the second plate.
 18. The method of claim 14, whereinactuating the shape memory alloy wire comprises one or more of:directing a current through the shape memory alloy wire; heating theshape memory alloy wire; and applying a magnetic field to the shapememory alloy wire.
 19. A hybrid actuation device comprising: a firstplate coupled to a second plate; an artificial muscle positioned betweenthe first plate and the second plate, the artificial muscle comprisingan electrode pair configured to electrostatically attract and hold thehybrid actuation device in the actuated state; and a first alignment aidpositioned between the first plate and the artificial muscle.
 20. Thehybrid actuation device of claim 19, wherein: the electrode pair of theartificial muscle is positioned together with a dielectric fluid withina housing; the housing comprises an expandable fluid region positionedapart from a perimeter of the first plate and the second plate; and thefirst plate and the second plate each comprises a rigid material and thefirst plate is coupled to the second plate using a hinge.